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Message-ID: <CAL_Jsq+J4QF5jvUOF_J71W0YWswTBSu=RZkwy+=gR2F-dwq7XA@mail.gmail.com>
Date: Mon, 16 May 2016 14:37:20 -0500
From: Rob Herring <robherring2@...il.com>
To: Pantelis Antoniou <pantelis.antoniou@...sulko.com>
Cc: Frank Rowand <frowand.list@...il.com>,
Matt Porter <mporter@...sulko.com>,
Grant Likely <grant.likely@...retlab.ca>,
Koen Kooi <koen@...inion.thruhere.net>,
Guenter Roeck <linux@...ck-us.net>,
Marek Vasut <marex@...x.de>,
Geert Uytterhoeven <geert@...ux-m68k.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Pantelis Antoniou <panto@...oniou-consulting.com>
Subject: Re: [PATCH v2 2/5] of: Support hashtable lookups for phandles
On Mon, May 16, 2016 at 11:52 AM, Pantelis Antoniou
<pantelis.antoniou@...sulko.com> wrote:
> When a device tree contains a lot of phandles, resolving one
> takes time because the original method uses a search against
> all nodes (not just the ones with phandles).
>
> Signed-off-by: Pantelis Antoniou <pantelis.antoniou@...sulko.com>
> ---
> drivers/of/base.c | 41 ++++++++++++++++++++++++++++++++++++++---
> drivers/of/dynamic.c | 8 ++++++++
> drivers/of/of_private.h | 33 +++++++++++++++++++++++++++++++++
> include/linux/of.h | 2 ++
> 4 files changed, 81 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index 20bbc2f..436a088 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -27,6 +27,7 @@
> #include <linux/slab.h>
> #include <linux/string.h>
> #include <linux/proc_fs.h>
> +#include <linux/rhashtable.h>
>
> #include "of_private.h"
>
> @@ -41,6 +42,18 @@ static const char *of_stdout_options;
>
> struct kset *of_kset;
>
> +const struct rhashtable_params of_phandle_ht_params = {
static
> + .key_offset = offsetof(struct device_node, phandle), /* base offset */
> + .key_len = sizeof(phandle),
> + .head_offset = offsetof(struct device_node, ht_node),
> + .automatic_shrinking = true,
> +};
> +
> +struct rhashtable *of_phandle_ht;
> +
> +/* default is false */
> +bool of_phandle_ht_is_disabled;
I think this should go. The unittest alone is not enough reason to keep.
> +
> /*
> * Used to protect the of_aliases, to hold off addition of nodes to sysfs.
> * This mutex must be held whenever modifications are being made to the
> @@ -162,6 +175,12 @@ int __of_attach_node_post(struct device_node *np)
> struct property *pp;
> int rc;
>
> + if (of_phandle_ht_available()) {
This can never be false as this function should only get called after init.
> + rc = of_phandle_ht_insert(np);
> + WARN(rc, "insert to phandle hash fail @%s\n",
> + of_node_full_name(np));
> + }
> +
> if (!IS_ENABLED(CONFIG_SYSFS))
> return 0;
>
> @@ -194,6 +213,17 @@ void __init of_core_init(void)
> struct device_node *np;
> int ret;
>
> + of_phandle_ht = kzalloc(sizeof(*of_phandle_ht), GFP_KERNEL);
> + if (!of_phandle_ht) {
> + pr_warn("devicetree: Failed to allocate hashtable\n");
> + return;
> + }
> + ret = rhashtable_init(of_phandle_ht, &of_phandle_ht_params);
> + if (ret) {
> + pr_warn("devicetree: Failed to initialize hashtable\n");
> + return;
> + }
> +
> /* Create the kset, and register existing nodes */
> mutex_lock(&of_mutex);
> of_kset = kset_create_and_add("devicetree", NULL, firmware_kobj);
> @@ -1073,9 +1103,14 @@ struct device_node *of_find_node_by_phandle(phandle handle)
> return NULL;
>
> raw_spin_lock_irqsave(&devtree_lock, flags);
> - for_each_of_allnodes(np)
> - if (np->phandle == handle)
> - break;
> + /* when we're ready use the hash table (and not disabled) */
> + if (of_phandle_ht_available() && !of_phandle_ht_is_disabled)
Just "if (of_phandle_ht)"
> + np = of_phandle_ht_lookup(handle);
> + else { /* fallback */
> + for_each_of_allnodes(np)
> + if (np->phandle == handle)
> + break;
> + }
> of_node_get(np);
> raw_spin_unlock_irqrestore(&devtree_lock, flags);
> return np;
> diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c
> index 34ca783..931b905 100644
> --- a/drivers/of/dynamic.c
> +++ b/drivers/of/dynamic.c
> @@ -11,6 +11,7 @@
> #include <linux/slab.h>
> #include <linux/string.h>
> #include <linux/proc_fs.h>
> +#include <linux/rhashtable.h>
>
> #include "of_private.h"
>
> @@ -44,6 +45,13 @@ EXPORT_SYMBOL(of_node_put);
> void __of_detach_node_post(struct device_node *np)
> {
> struct property *pp;
> + int rc;
> +
> + if (of_phandle_ht_available()) {
Likewise, this can't be false either.
> + rc = of_phandle_ht_remove(np);
> + WARN(rc, "remove from phandle hash fail @%s\n",
> + of_node_full_name(np));
> + }
>
> if (!IS_ENABLED(CONFIG_SYSFS))
> return;
> diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
> index 10b0342..386ae71 100644
> --- a/drivers/of/of_private.h
> +++ b/drivers/of/of_private.h
> @@ -101,4 +101,37 @@ static inline int of_overlay_init(void)
> }
> #endif
>
> +extern const struct rhashtable_params of_phandle_ht_params;
> +extern struct rhashtable *of_phandle_ht;
> +
> +/* for unittest use */
> +extern bool of_phandle_ht_is_disabled;
> +
> +static inline bool of_phandle_ht_available(void)
> +{
> + return of_phandle_ht != NULL;
> +}
> +
> +static inline int of_phandle_ht_insert(struct device_node *np)
> +{
> + if (!np || !np->phandle)
> + return 0;
> + return rhashtable_insert_fast(of_phandle_ht,
> + &np->ht_node, of_phandle_ht_params);
> +}
> +
> +static inline int of_phandle_ht_remove(struct device_node *np)
> +{
> + if (!np || !np->phandle)
> + return 0;
> + return rhashtable_remove_fast(of_phandle_ht,
> + &np->ht_node, of_phandle_ht_params);
> +}
> +
> +static inline struct device_node *of_phandle_ht_lookup(phandle handle)
> +{
> + return rhashtable_lookup_fast(of_phandle_ht,
> + &handle, of_phandle_ht_params);
> +}
> +
> #endif /* _LINUX_OF_PRIVATE_H */
> diff --git a/include/linux/of.h b/include/linux/of.h
> index 18a8e59..9de9a3f 100644
> --- a/include/linux/of.h
> +++ b/include/linux/of.h
> @@ -25,6 +25,7 @@
> #include <linux/notifier.h>
> #include <linux/property.h>
> #include <linux/list.h>
> +#include <linux/rhashtable.h>
>
> #include <asm/byteorder.h>
> #include <asm/errno.h>
> @@ -52,6 +53,7 @@ struct device_node {
> phandle phandle;
> const char *full_name;
> struct fwnode_handle fwnode;
> + struct rhash_head ht_node;
Place next to .phandle as both will be accessed at the same time.
>
> struct property *properties;
> struct property *deadprops; /* removed properties */
> --
> 1.7.12
>
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